A certain brand of at white interior latex paint claims one-coat coverage of 400 square feet per gallon. The standard deviation is known to be 20. A sample of 16 gallons is tested.
(a) At α = .05 in a left-tailed test, find the risk and power assuming that the true mean is really 380 square feet per gallon.
(b) Construct a left-tailed power curve, using increments of 5 square feet (400, 395, 390, 385, 380).